The feasibility of making calcium carbonate-calcium phosphate (CaCO(3)-CaP) mixed cements, comprising at least 40% (w/w) CaCO(3) in the dry powder ingredients, has been demonstrated. Several original cement compositions were obtained by mixing metastable crystalline CaCO(3) phases with metastable amorphous or crystalline CaP powders in aqueous medium. The cements set within at most 1 h at 37 de...

Increasing environmental pollution in urban areas has been endangering the survival of carbonate stones in monuments and statuary for many decades. Numerous conservation treatments have been applied for the protection and consolidation of these works of art. Most of them, however, either release dangerous gases during curing or show very little efficacy. Bacterially induced carbonate mineraliza...

Microbialites (benthic microbial carbonate deposits) were discovered in a hypersaline alkaline lake on Eleuthera Island (Bahamas). From the edge towards the centre of the lake, four main zones of precipitation could be distinguished: (1) millimetre-sized clumps of Mg-calcite on a thin microbial mat; (2) thicker and continuous carbonate crusts with columnar morphologies; (3) isolated patches of ...

Tartaric acid (TA) changes short-term mechanical behavior and phase composition of sodium-metasilicate activated calcium-aluminate cement blend with fly ash, type F, when used as a set control additive to allow sufficient pumping time for underground well placement. The present work focuses on TA effect on self-healing properties of the blend under steam or alkali carbonate environments at 270 ...

This study investigated the hydration characteristics and strength development of calcium sulfoaluminate-belite (CSAB) cements incorporating calcium carbonate (CC) powders with various particle size distributions and different gypsum amounts. In general, the CSAB hydration was accelerated by the CC powder, but the acceleration and resulting strength improvement were more effective with finer CC...

ID No: 65 ABSTRACT This research studies the self-healing potential of early cracks in cement-based materials incorporating carbonic anhydrase (CA) bacteria. CA bacteria can accelerate the CO2 hydrated reaction then transfer CO2 to HCO3 which can react with soluble Ca(OH)2 on the surface of specimens. Calcium carbonate deposits because of the reaction of HCO3 with Ca.This research studies the s...

Petrographic study of the Frewens sandstone, Upper Cretaceous Frontier Formation, documents reservoir-scale diagenetic heterogeneity. Iron-bearing calcite cement occurs as large concretions that generally follow bedding and are most common near the top of the sandstone. Median thickness of the concretions is 0.6 m, length 4.5 m, and width 5.7 m; median volume is 5.2 m. Concretions comprise 12% ...